| … | |
… | |
| 129 | Reads or writes C<length> bytes from the specified C<fh> and C<offset> |
129 | Reads or writes C<length> bytes from the specified C<fh> and C<offset> |
| 130 | into the scalar given by C<data> and offset C<dataoffset> and calls the |
130 | into the scalar given by C<data> and offset C<dataoffset> and calls the |
| 131 | callback without the actual number of bytes read (or -1 on error, just |
131 | callback without the actual number of bytes read (or -1 on error, just |
| 132 | like the syscall). |
132 | like the syscall). |
| 133 | |
133 | |
| 134 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at |
134 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at |
| 135 | offset C<0> within the scalar: |
135 | offset C<0> within the scalar: |
| 136 | |
136 | |
| 137 | aio_read $fh, 7, 15, $buffer, 0, sub { |
137 | aio_read $fh, 7, 15, $buffer, 0, sub { |
| 138 | $_[0] > 0 or die "read error: $!"; |
138 | $_[0] > 0 or die "read error: $!"; |
| 139 | print "read $_[0] bytes: <$buffer>\n"; |
139 | print "read $_[0] bytes: <$buffer>\n"; |
| 140 | }; |
140 | }; |
| 141 | |
141 | |
| 142 | =item aio_readahead $fh,$offset,$length, $callback |
142 | =item aio_readahead $fh,$offset,$length, $callback |
| 143 | |
143 | |
| 144 | Asynchronously reads the specified byte range into the page cache, using |
144 | Asynchronously reads the specified byte range into the page cache, using |
| 145 | the C<readahead> syscall. If that syscall doesn't exist the status will be |
145 | the C<readahead> syscall. If that syscall doesn't exist (likely if your OS |
| 146 | C<-1> and C<$!> is set to ENOSYS. |
146 | isn't Linux) the status will be C<-1> and C<$!> is set to ENOSYS. |
| 147 | |
147 | |
| 148 | readahead() populates the page cache with data from a file so that |
148 | readahead() populates the page cache with data from a file so that |
| 149 | subsequent reads from that file will not block on disk I/O. The C<$offset> |
149 | subsequent reads from that file will not block on disk I/O. The C<$offset> |
| 150 | argument specifies the starting point from which data is to be read and |
150 | argument specifies the starting point from which data is to be read and |
| 151 | C<$length> specifies the number of bytes to be read. I/O is performed in |
151 | C<$length> specifies the number of bytes to be read. I/O is performed in |
